Piloting system for electric inverter

Abstract

The MOSFETs or IGBTs of respective arms of an electronic inverter are in series with SCRs or TRIACs triggered into conduction during intervals of intended conduction of the respective MOSFETs or IGBTs connected to the high level rectifier terminal. The piloting of the SCRs or TRIACs is effected from the piloting of the MOSFETs or with delay or in a conditional manner. The circuit eliminates the effective transience on the inverter output.

I claim: 
     
       1. An electronic inverter, comprising: a rectifying network having an alternating current input and direct current output;   a plurality of arms connected across said direct current output and including two field effect transistors having source, drain and gate terminals, the source and drain terminals of the two field effect transistors of each arm being connected in series, each arm having an output terminal connected to an alternating inductive current load in the form of an electric motor;   timing means connected to the gates of said field effect transistors for cyclically rendering alternating ones of said field effect transistors of each arm conductive, thereby energizing said load with alternating current;   a respective protective diode bridged across each of said field effect transistors;   a respective gate-triggerable current control element selected from a triac and an SCR in series with one of the field effect transistors of each of said arms and a respective terminal of said direct current output, and assigned to the respective field effect transistor; and   piloting circuitry for said gate-triggerable current control elements for triggering the current control elements into conductivity cyclically only during required intervals of conductivity of the field effect transistors to which the current control elements are assigned, said piloting circuitry responding to initiation of conductivity of the respective field effect transistor with a delay.   
     
     
       2. The inverter defined in claim 1 wherein said piloting circuitry requires a certain triggering potential above preventing false triggering of said current control elements by voltage transients. 
     
     
       3. The inverter defined in claim 1 wherein said field effect transistors are insulated gate bipolar transistors. 
     
     
       4. The inverter defined in claim 1 wherein said current control elements are metal oxide semiconductor field effect transistors. 
     
     
       5. The inverter defined in claim 4 wherein said current control elements are located between a positive terminal of said direct current output and the respective metal oxide semiconductor field effect transistor. 
     
     
       6. The inverter defined in claim 5 wherein each of said current control elements is a silicon controlled rectifier. 
     
     
       7. The inverter defined in claim 5 wherein each of said current control elements is a TRIAC.